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Randy Dunlapf7f84f32009-02-22 12:15:45 -08001<?xml version="1.0" encoding="UTF-8"?>
2<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
3 "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []>
4
5<book id="LinuxDriversAPI">
6 <bookinfo>
7 <title>Linux Device Drivers</title>
8
9 <legalnotice>
10 <para>
11 This documentation is free software; you can redistribute
12 it and/or modify it under the terms of the GNU General Public
13 License as published by the Free Software Foundation; either
14 version 2 of the License, or (at your option) any later
15 version.
16 </para>
17
18 <para>
19 This program is distributed in the hope that it will be
20 useful, but WITHOUT ANY WARRANTY; without even the implied
21 warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
22 See the GNU General Public License for more details.
23 </para>
24
25 <para>
26 You should have received a copy of the GNU General Public
27 License along with this program; if not, write to the Free
28 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
29 MA 02111-1307 USA
30 </para>
31
32 <para>
33 For more details see the file COPYING in the source
34 distribution of Linux.
35 </para>
36 </legalnotice>
37 </bookinfo>
38
39<toc></toc>
40
41 <chapter id="Basics">
42 <title>Driver Basics</title>
43 <sect1><title>Driver Entry and Exit points</title>
44!Iinclude/linux/init.h
45 </sect1>
46
47 <sect1><title>Atomic and pointer manipulation</title>
Randy Dunlap88b68032010-03-01 22:06:25 -080048!Iarch/x86/include/asm/atomic.h
Randy Dunlapf7f84f32009-02-22 12:15:45 -080049 </sect1>
50
51 <sect1><title>Delaying, scheduling, and timer routines</title>
52!Iinclude/linux/sched.h
53!Ekernel/sched.c
Randy Dunlapee2f1542010-10-26 14:17:25 -070054!Iinclude/linux/completion.h
Randy Dunlapf7f84f32009-02-22 12:15:45 -080055!Ekernel/timer.c
56 </sect1>
Randy Dunlapee2f1542010-10-26 14:17:25 -070057 <sect1><title>Wait queues and Wake events</title>
58!Iinclude/linux/wait.h
59!Ekernel/wait.c
60 </sect1>
Randy Dunlapf7f84f32009-02-22 12:15:45 -080061 <sect1><title>High-resolution timers</title>
62!Iinclude/linux/ktime.h
63!Iinclude/linux/hrtimer.h
64!Ekernel/hrtimer.c
65 </sect1>
66 <sect1><title>Workqueues and Kevents</title>
67!Ekernel/workqueue.c
68 </sect1>
69 <sect1><title>Internal Functions</title>
70!Ikernel/exit.c
71!Ikernel/signal.c
72!Iinclude/linux/kthread.h
73!Ekernel/kthread.c
74 </sect1>
75
76 <sect1><title>Kernel objects manipulation</title>
77<!--
78X!Iinclude/linux/kobject.h
79-->
80!Elib/kobject.c
81 </sect1>
82
83 <sect1><title>Kernel utility functions</title>
84!Iinclude/linux/kernel.h
85!Ekernel/printk.c
86!Ekernel/panic.c
87!Ekernel/sys.c
88!Ekernel/rcupdate.c
89 </sect1>
90
91 <sect1><title>Device Resource Management</title>
92!Edrivers/base/devres.c
93 </sect1>
94
95 </chapter>
96
97 <chapter id="devdrivers">
98 <title>Device drivers infrastructure</title>
99 <sect1><title>Device Drivers Base</title>
100<!--
101X!Iinclude/linux/device.h
102-->
103!Edrivers/base/driver.c
104!Edrivers/base/core.c
105!Edrivers/base/class.c
106!Edrivers/base/firmware_class.c
107!Edrivers/base/transport_class.c
108<!-- Cannot be included, because
109 attribute_container_add_class_device_adapter
110 and attribute_container_classdev_to_container
111 exceed allowed 44 characters maximum
112X!Edrivers/base/attribute_container.c
113-->
114!Edrivers/base/sys.c
115<!--
116X!Edrivers/base/interface.c
117-->
Uwe Kleine-König44f28bd2010-06-21 16:11:44 +0200118!Iinclude/linux/platform_device.h
Randy Dunlapf7f84f32009-02-22 12:15:45 -0800119!Edrivers/base/platform.c
120!Edrivers/base/bus.c
121 </sect1>
122 <sect1><title>Device Drivers Power Management</title>
123!Edrivers/base/power/main.c
124 </sect1>
125 <sect1><title>Device Drivers ACPI Support</title>
126<!-- Internal functions only
127X!Edrivers/acpi/sleep/main.c
128X!Edrivers/acpi/sleep/wakeup.c
129X!Edrivers/acpi/motherboard.c
130X!Edrivers/acpi/bus.c
131-->
132!Edrivers/acpi/scan.c
133!Idrivers/acpi/scan.c
134<!-- No correct structured comments
135X!Edrivers/acpi/pci_bind.c
136-->
137 </sect1>
138 <sect1><title>Device drivers PnP support</title>
139!Idrivers/pnp/core.c
140<!-- No correct structured comments
141X!Edrivers/pnp/system.c
142 -->
143!Edrivers/pnp/card.c
144!Idrivers/pnp/driver.c
145!Edrivers/pnp/manager.c
146!Edrivers/pnp/support.c
147 </sect1>
148 <sect1><title>Userspace IO devices</title>
149!Edrivers/uio/uio.c
150!Iinclude/linux/uio_driver.h
151 </sect1>
152 </chapter>
153
154 <chapter id="parportdev">
155 <title>Parallel Port Devices</title>
156!Iinclude/linux/parport.h
157!Edrivers/parport/ieee1284.c
158!Edrivers/parport/share.c
159!Idrivers/parport/daisy.c
160 </chapter>
161
162 <chapter id="message_devices">
163 <title>Message-based devices</title>
164 <sect1><title>Fusion message devices</title>
165!Edrivers/message/fusion/mptbase.c
166!Idrivers/message/fusion/mptbase.c
167!Edrivers/message/fusion/mptscsih.c
168!Idrivers/message/fusion/mptscsih.c
169!Idrivers/message/fusion/mptctl.c
170!Idrivers/message/fusion/mptspi.c
171!Idrivers/message/fusion/mptfc.c
172!Idrivers/message/fusion/mptlan.c
173 </sect1>
174 <sect1><title>I2O message devices</title>
175!Iinclude/linux/i2o.h
176!Idrivers/message/i2o/core.h
177!Edrivers/message/i2o/iop.c
178!Idrivers/message/i2o/iop.c
179!Idrivers/message/i2o/config-osm.c
180!Edrivers/message/i2o/exec-osm.c
181!Idrivers/message/i2o/exec-osm.c
182!Idrivers/message/i2o/bus-osm.c
183!Edrivers/message/i2o/device.c
184!Idrivers/message/i2o/device.c
185!Idrivers/message/i2o/driver.c
186!Idrivers/message/i2o/pci.c
187!Idrivers/message/i2o/i2o_block.c
188!Idrivers/message/i2o/i2o_scsi.c
189!Idrivers/message/i2o/i2o_proc.c
190 </sect1>
191 </chapter>
192
193 <chapter id="snddev">
194 <title>Sound Devices</title>
195!Iinclude/sound/core.h
196!Esound/sound_core.c
197!Iinclude/sound/pcm.h
198!Esound/core/pcm.c
199!Esound/core/device.c
200!Esound/core/info.c
201!Esound/core/rawmidi.c
202!Esound/core/sound.c
203!Esound/core/memory.c
204!Esound/core/pcm_memory.c
205!Esound/core/init.c
206!Esound/core/isadma.c
207!Esound/core/control.c
208!Esound/core/pcm_lib.c
209!Esound/core/hwdep.c
210!Esound/core/pcm_native.c
211!Esound/core/memalloc.c
212<!-- FIXME: Removed for now since no structured comments in source
213X!Isound/sound_firmware.c
214-->
215 </chapter>
216
217 <chapter id="uart16x50">
218 <title>16x50 UART Driver</title>
219!Iinclude/linux/serial_core.h
220!Edrivers/serial/serial_core.c
221!Edrivers/serial/8250.c
222 </chapter>
223
224 <chapter id="fbdev">
225 <title>Frame Buffer Library</title>
226
227 <para>
228 The frame buffer drivers depend heavily on four data structures.
229 These structures are declared in include/linux/fb.h. They are
230 fb_info, fb_var_screeninfo, fb_fix_screeninfo and fb_monospecs.
231 The last three can be made available to and from userland.
232 </para>
233
234 <para>
235 fb_info defines the current state of a particular video card.
236 Inside fb_info, there exists a fb_ops structure which is a
237 collection of needed functions to make fbdev and fbcon work.
238 fb_info is only visible to the kernel.
239 </para>
240
241 <para>
242 fb_var_screeninfo is used to describe the features of a video card
243 that are user defined. With fb_var_screeninfo, things such as
244 depth and the resolution may be defined.
245 </para>
246
247 <para>
248 The next structure is fb_fix_screeninfo. This defines the
249 properties of a card that are created when a mode is set and can't
250 be changed otherwise. A good example of this is the start of the
251 frame buffer memory. This "locks" the address of the frame buffer
252 memory, so that it cannot be changed or moved.
253 </para>
254
255 <para>
256 The last structure is fb_monospecs. In the old API, there was
257 little importance for fb_monospecs. This allowed for forbidden things
258 such as setting a mode of 800x600 on a fix frequency monitor. With
259 the new API, fb_monospecs prevents such things, and if used
260 correctly, can prevent a monitor from being cooked. fb_monospecs
261 will not be useful until kernels 2.5.x.
262 </para>
263
264 <sect1><title>Frame Buffer Memory</title>
265!Edrivers/video/fbmem.c
266 </sect1>
267<!--
268 <sect1><title>Frame Buffer Console</title>
269X!Edrivers/video/console/fbcon.c
270 </sect1>
271-->
272 <sect1><title>Frame Buffer Colormap</title>
273!Edrivers/video/fbcmap.c
274 </sect1>
275<!-- FIXME:
276 drivers/video/fbgen.c has no docs, which stuffs up the sgml. Comment
277 out until somebody adds docs. KAO
278 <sect1><title>Frame Buffer Generic Functions</title>
279X!Idrivers/video/fbgen.c
280 </sect1>
281KAO -->
282 <sect1><title>Frame Buffer Video Mode Database</title>
283!Idrivers/video/modedb.c
284!Edrivers/video/modedb.c
285 </sect1>
286 <sect1><title>Frame Buffer Macintosh Video Mode Database</title>
287!Edrivers/video/macmodes.c
288 </sect1>
289 <sect1><title>Frame Buffer Fonts</title>
290 <para>
291 Refer to the file drivers/video/console/fonts.c for more information.
292 </para>
293<!-- FIXME: Removed for now since no structured comments in source
294X!Idrivers/video/console/fonts.c
295-->
296 </sect1>
297 </chapter>
298
299 <chapter id="input_subsystem">
300 <title>Input Subsystem</title>
Dmitry Torokhovd69249f2009-11-16 22:12:20 -0800301 <sect1><title>Input core</title>
Randy Dunlapf7f84f32009-02-22 12:15:45 -0800302!Iinclude/linux/input.h
303!Edrivers/input/input.c
304!Edrivers/input/ff-core.c
305!Edrivers/input/ff-memless.c
Dmitry Torokhovd69249f2009-11-16 22:12:20 -0800306 </sect1>
307 <sect1><title>Polled input devices</title>
308!Iinclude/linux/input-polldev.h
309!Edrivers/input/input-polldev.c
310 </sect1>
311 <sect1><title>Matrix keyboars/keypads</title>
312!Iinclude/linux/input/matrix_keypad.h
313 </sect1>
Dmitry Torokhov36203c42009-12-04 10:22:23 -0800314 <sect1><title>Sparse keymap support</title>
315!Iinclude/linux/input/sparse-keymap.h
316!Edrivers/input/sparse-keymap.c
317 </sect1>
Randy Dunlapf7f84f32009-02-22 12:15:45 -0800318 </chapter>
319
320 <chapter id="spi">
321 <title>Serial Peripheral Interface (SPI)</title>
322 <para>
323 SPI is the "Serial Peripheral Interface", widely used with
324 embedded systems because it is a simple and efficient
325 interface: basically a multiplexed shift register.
326 Its three signal wires hold a clock (SCK, often in the range
327 of 1-20 MHz), a "Master Out, Slave In" (MOSI) data line, and
328 a "Master In, Slave Out" (MISO) data line.
329 SPI is a full duplex protocol; for each bit shifted out the
330 MOSI line (one per clock) another is shifted in on the MISO line.
331 Those bits are assembled into words of various sizes on the
332 way to and from system memory.
333 An additional chipselect line is usually active-low (nCS);
334 four signals are normally used for each peripheral, plus
335 sometimes an interrupt.
336 </para>
337 <para>
338 The SPI bus facilities listed here provide a generalized
339 interface to declare SPI busses and devices, manage them
340 according to the standard Linux driver model, and perform
341 input/output operations.
342 At this time, only "master" side interfaces are supported,
343 where Linux talks to SPI peripherals and does not implement
344 such a peripheral itself.
345 (Interfaces to support implementing SPI slaves would
346 necessarily look different.)
347 </para>
348 <para>
349 The programming interface is structured around two kinds of driver,
350 and two kinds of device.
351 A "Controller Driver" abstracts the controller hardware, which may
352 be as simple as a set of GPIO pins or as complex as a pair of FIFOs
353 connected to dual DMA engines on the other side of the SPI shift
354 register (maximizing throughput). Such drivers bridge between
355 whatever bus they sit on (often the platform bus) and SPI, and
356 expose the SPI side of their device as a
357 <structname>struct spi_master</structname>.
358 SPI devices are children of that master, represented as a
359 <structname>struct spi_device</structname> and manufactured from
360 <structname>struct spi_board_info</structname> descriptors which
361 are usually provided by board-specific initialization code.
362 A <structname>struct spi_driver</structname> is called a
363 "Protocol Driver", and is bound to a spi_device using normal
364 driver model calls.
365 </para>
366 <para>
367 The I/O model is a set of queued messages. Protocol drivers
368 submit one or more <structname>struct spi_message</structname>
369 objects, which are processed and completed asynchronously.
370 (There are synchronous wrappers, however.) Messages are
371 built from one or more <structname>struct spi_transfer</structname>
372 objects, each of which wraps a full duplex SPI transfer.
373 A variety of protocol tweaking options are needed, because
374 different chips adopt very different policies for how they
375 use the bits transferred with SPI.
376 </para>
377!Iinclude/linux/spi/spi.h
378!Fdrivers/spi/spi.c spi_register_board_info
379!Edrivers/spi/spi.c
380 </chapter>
381
382 <chapter id="i2c">
383 <title>I<superscript>2</superscript>C and SMBus Subsystem</title>
384
385 <para>
386 I<superscript>2</superscript>C (or without fancy typography, "I2C")
387 is an acronym for the "Inter-IC" bus, a simple bus protocol which is
388 widely used where low data rate communications suffice.
389 Since it's also a licensed trademark, some vendors use another
390 name (such as "Two-Wire Interface", TWI) for the same bus.
391 I2C only needs two signals (SCL for clock, SDA for data), conserving
392 board real estate and minimizing signal quality issues.
393 Most I2C devices use seven bit addresses, and bus speeds of up
394 to 400 kHz; there's a high speed extension (3.4 MHz) that's not yet
395 found wide use.
396 I2C is a multi-master bus; open drain signaling is used to
397 arbitrate between masters, as well as to handshake and to
398 synchronize clocks from slower clients.
399 </para>
400
401 <para>
402 The Linux I2C programming interfaces support only the master
403 side of bus interactions, not the slave side.
404 The programming interface is structured around two kinds of driver,
405 and two kinds of device.
406 An I2C "Adapter Driver" abstracts the controller hardware; it binds
407 to a physical device (perhaps a PCI device or platform_device) and
408 exposes a <structname>struct i2c_adapter</structname> representing
409 each I2C bus segment it manages.
410 On each I2C bus segment will be I2C devices represented by a
411 <structname>struct i2c_client</structname>. Those devices will
412 be bound to a <structname>struct i2c_driver</structname>,
413 which should follow the standard Linux driver model.
414 (At this writing, a legacy model is more widely used.)
415 There are functions to perform various I2C protocol operations; at
416 this writing all such functions are usable only from task context.
417 </para>
418
419 <para>
420 The System Management Bus (SMBus) is a sibling protocol. Most SMBus
421 systems are also I2C conformant. The electrical constraints are
422 tighter for SMBus, and it standardizes particular protocol messages
423 and idioms. Controllers that support I2C can also support most
424 SMBus operations, but SMBus controllers don't support all the protocol
425 options that an I2C controller will.
426 There are functions to perform various SMBus protocol operations,
427 either using I2C primitives or by issuing SMBus commands to
428 i2c_adapter devices which don't support those I2C operations.
429 </para>
430
431!Iinclude/linux/i2c.h
432!Fdrivers/i2c/i2c-boardinfo.c i2c_register_board_info
433!Edrivers/i2c/i2c-core.c
434 </chapter>
435
436</book>